Why did the front plug/connection come into being on TCs?

Good question. My thinking is that it is closer to most power centers on the TCer's (they seem to be up front so less run of cords to the back of the truck then back to the front in the camper), also at the back of the truck most people wanted to tow something so they did not want to use that plug and there was not another convenient place to put it at the back and still reach it when loaded.